Control device for a motor vehicle parking brake

ABSTRACT

A control device for a parking brake for a vehicle includes an electric motor which rotates a crank to activate the parking brake with the provision of a disk having two concentric conductive tracks which are interrupted by an insulating space; the disk is rotated by the drive shaft to control the supply of current for driving the electric motor.

FIELD OF THE INVENTION

The invention relates to a control device for a parking brake for amotor vehicle.

The invention concerns more particularly, but not exclusively, such acontrol device for a golf buggy, in particular of the kind aimed at bythe Patent Application FR 88 07243 (FR-A-2 631 902) filed on the 31stMay, 1988 in the Applicant's name.

The object of the invention is primarily to improve the efficiency ofthe parking brake.

SUMMARY OF THE INVENTION

According to the invention, the control device for the parking brake ischaracterized in that it includes motor means capable of actuating theparking brake and control means for the starting, in particular, theautomatic starting of the motor means.

Preferably, the control device includes a rotary crank capable ofdriving a mechanical linkage acting on the parking brake, the motormeans being capable of ensuring the rotation of the crank from an"engagement" position to a "disengagement" position and vice versa.

Preferably, the engagement and disengagement positions of the crank arediametrically opposed.

The motor means capable of actuating the parking brake and in particularthe crank are advantageously constituted by an electric motor,optionally combined with a reducing gear that is, in particular, capableof driving the crank.

A device including a disk provided with two concentric tracks whereof atleast one is open, and comprises an insulating space separating its twoends, is fixed on a drive shaft of the crank and is capable ofcooperating with brushes coming into contact with these tracks to ensurethe electric power supply for the motor so as to produce the stopping ofthe shaft and of the crank in a given position and to permit themovement of this crank only to pass from the engaged position to thedisengaged position, or vice versa.

According to an advantageous mode of embodiment, in particular for agolf buggy, the motor means of the parking brake are capable of actingon a normal braking device, the mechanical linkage between the motormeans of the parking brake and the normal braking device being ensuredby a loss of motion device making it possible to retain a conventionalactuation of the normal braking device by acting on the brake pedal.

The engaging or disengaging actuation can be manual, in particular, bymeans of push buttons and/or contacts that are capable of starting themotor means for actuating the parking brake in the engagement ordisengagement direction.

As a variant, the actuation of engaging the parking brake can be manual,whilst provision is made for an automatic disengagement actuation duringaction on the accelerator pedal.

Advantageously, provision is made for an automatic actuation of theengagement of the parking brake in response to the absence of any actionon the accelerator pedal; provision may be made for an adjustable timelag, in particular of the order of at least one second, for actuatingthe engagement of the parking brake after the action on the acceleratorpedal has ceased.

In the case of a vehicle, in particular a golf buggy which compriseselectric drive motors powered by a chopped current, the control devicemay includes means for controlling a control relay sensing theconductive or blocked state of a transistor energizing the electricdrive motors.

Provision may be made for means sensing the speed of motion of thevehicle capable of only permitting the automatic engagement of theparking brake when the vehicle is stationary, or when its speed is lessthan a predetermined value.

Apart from the arrangements set out above, the invention consists of acertain number of other arrangements which will be discussed in greaterdetail below in conjunction with particular modes of embodimentdescribed with reference to the attached drawings, but which are in noway restrictive.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 of these drawings is an electric circuit diagram of a parkingbrake control device according to the invention, with manual engagementand automatic disengagement.

FIG. 2 is a circuit diagram illustrating a variant of the embodiment ofFIG. 1, still with manual engagement and automatic disengagement.

FIG. 3 is a another circuit diagram of a parking brake control deviceaccording to the invention with manual engagement and disengagement.

FIG. 4 is a circuit diagram of a variant of the embodiment of theparking brake control device with automatic engagement anddisengagement.

FIG. 5 is a more detailed circuit diagram of the control device of FIG.4.

Finally, FIG. 6 is an elevational view of a front portion of a golfbuggy fitted with a parking brake control device according to theinvention.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1 of the drawings, there may be seen a parking brakecontrol device C for a motor vehicle (not represented). Only amechanical linkage 1 has been schematically shown which allows theschematically represented parking brake P to be acted on. The controldevice C includes an electric motor 2 capable of actuating the parkingbrake P. For this purpose, a crank 3 is fixed on the shaft 4 of themotor 2 or of a reducing gear (not shown) that is driven by the motor 2.The crank 3 drives the rod 1 and can pass from the position in a solidline shown in FIG. 1 to a diametrically opposed position. The positionin a solid line may correspond to the engagement of the parking brake,whilst the diametrically opposite position corresponds to the disengagedposition.

The passing of the crank 3 from one position to the other is ensured bya one half turn rotation of the shaft 4, either always in the samedirection, or in the opposite direction.

The electric motor 2 is of the direct current type. A terminal of themotor 2 is connected to the--power supply line via the operativeposition of a contact z of a relay Z. In its rest position representedin a solid line in FIG. 1, the contact z short-circuits the motor initself by means of a connection 5 to the other terminal of the motor.This other terminal of the motor is connected to the cathode of a diode6 whose anode is connected to a contact 7 capable of being in apermanent electrical connection with a conductive annular inner track 8that is closed in itself. This track 8 is provided concentrically on aninsulating disk 9 fixed to the shaft 4. This disk 9 forms a cam whichactuates the stopping of the motor 2 and of the shaft 4 in the engagedor disengaged position.

The disk 9 comprises another, outer conductive track 10 which is open,concentric with the track 8 and electrically connected to the latter,the two adjoining ends of this track 10 being separated by an insulatingspace 11 forming a non-conductive "hole". Provision is made for twodiametrically opposed contacts 12, 13 to come to bear on the annularzone of the track 10.

The contact 12 corresponding to the engagement actuation is electricallyconnected to a terminal of a push button 14, whose other terminal isconnected to the + electric power supply line.

The contact 13 assigned to the disengagement is connected to a terminalof a contact 15 whose other terminal is connected to the + line.

The closing of the contact 15 is actuated by the accelerator pedal (notrepresented) of the motor vehicle. When the driver presses on thispedal, he produces the closing of the contact 15.

The control winding 16 of the relay Z is disposed between the contact 7and the - power supply line.

The operation of the control device of FIG. 1 is as follows.

It will be assumed that the control device is in the "disengaged"position of the parking brake, that is to say, that the crank 3 occupiesa position diametrically opposed to that of FIG. 1, as does theinsulating space 11 which is situated under the contact 13.

When the driver wishes to obtain the engagement of the parking brake, itsuffices for him to depress the push button 14 for a minimum period, forthe shaft 4 to complete a half turn, that is to say, for approximately1/2 second. The relay Z is energized because the connection is ensuredbetween the + line and the - line by the contact 12, the track 10 which,in the disengaged position is situated under the contact 12, the track8, the contact 7 and the connection between the winding 16 and thiscontact 7. The relay Z causes the contact z to pass from the restposition (a solid line) to the operative position (dashes), whichensures the energizing of the motor 2 which starts to turn, whilesimultaneously driving the crank 3 and the disk 9.

When the shaft 4 has completed a 1/2 turn, the crank 3 will havedisplaced the rod 1 into the engagement position (the position in FIG.1). Simultaneously, the disk 9 will have turned relative to the contacts7, 12 and 13 and the insulating space 11 will be situated under thecontact 12, while the contact 13 will bear on the track 10. The arrivalof the insulating space 11 under the contact 12 cuts the power supply tothe motor 2, which stops in the engaged position.

Since the relay Z is no longer excited, the contact z returns to itsrest position shown in a solid line, which ensures the short-circuitingof the motor 2 and its precise stopping.

When the driver presses on the accelerator pedal, the contact 15 isclosed and ensures the power supply to the coil 16 of the relay Z viathe contact 13 which at this moment, is in contact with the track 10.The motor 2 will again complete a 1/2 turn as explained above, causingthe crank 3 to pass from the engagement position to the disengagementposition. The release of the parking brake is produced approximately 1/2a second after the accelerator pedal has been pressed.

FIG. 2 shows a control device of the same kind as that of FIG. 1.However, the control push button 14 is combined with a relay X intendedto ensure that the power supply is maintained in the case where the pushbutton 14 has been released before the crank 3 has completed its 1/2turn.

The relay X includes a winding 17 disposed between the - power supplyline and the contact 12. This relay X includes a normally open contact xdisposed in parallel with the push button 14 between the + line and thecontact 12.

The operation is similar to that described with reference to FIG. 1.However, an action, even a very rapid action on the push button 14,suffices to produce the locking of the parking brake since this actionproduces the closing of the normally open contact x by the relay X,which contact maintains the power supply to the motor 2 even if the pushbutton 14 is released.

FIG. 3 is a circuit diagram of the control device similar to that ofFIGS. 1 and 2 wherein, however, the engagement and disengagementactuation is manual and is ensured by means of a switch 18 including abar 19, connected to the + line, which can be placed either into therest position represented in a solid line in FIG. 3, or into anoperative position where it is in contact with a contact piece 20connected to the contact 12 or with a contact piece 21 connected to thecontact 13.

Preferably, provision is made for resilient restoring means forreturning the bar 19 into its median position where it is not in contactwith any contact piece.

The manual displacement of the bar 19 so as to place it into contactwith the contact piece 20 and maintaining this contact for approximatelya 1/2 second, makes it possible to obtain the locking of the parkingbrake.

The disengagement is obtained by manually displacing the bar 19 to bringit into contact with the contact piece 21 and maintaining it there forapproximately a 1/2 second in this position.

To avoid having to hold the bar 19 for a time sufficient for theengagement or disengagement, provision may be made for self-holdingrelays for each of the contact pieces 20, 21, similar to the relays X ofFIG. 2.

The circuit diagram of the control device of FIG. 4 is largely similarto that of FIG. 3. However, the manual switch 18 has been replaced by arelay Y, whose coil 22 is controlled by an independent circuit E. Amovable bar y of this relay replaces the bar 19 of FIG. 3.

A safety switch 23 is mounted in the electric line connecting theterminal 20 of the bar y to the contact 12. This switch 23 may assumethe position represented in a solid line in FIG. 4 where it ensures theconnection between the terminal of the bar y and the contact 12. Theswitch 23 may assume a second position where it connects the terminal 20of the bar y to a line 24 connected to the contact 13, allowing theparking brake to be disengaged.

Referring to FIG. 5, the detailed electric circuit diagram may be seenof a control device with automatic engagement and disengagement of thetype described with reference to FIG. 4.

The circuit diagram of FIG. 5 is provided for a parking brake controldevice in a golf buggy driven by an electric motor. Preferably, fourelectric motors 25, 26, 27, 28 are associated with each of the fourwheels of the vehicle in accordance with the FR-A-2 631 902.

The flow of the current in the drive motors 25-28 is controlled by a setof MOS transistors 29, disposed in parallel, only one of which has beenshown.

Each transistor 29, for example of the N channel type, has its sourceearthed, with the possible interposition of a resistor 30 (shunt) andits drain connected to an electric line 31 intended to be connected toone of the terminals of the motors 25-28 via a switch 32.

The other terminal of each of the motors 25-28 is intended to beconnected to the + power line via another contact of the same switch 32.

It will be immediately understood, as has incidentally been explained inthe FR-A-2 631 902, that when the switch 32 is in one of its operativepositions ensuring the connection of the + line with one of theterminals of the motors 25-28, these motors will be energized when thetransistors 29 are conductive and will not be energized when thetransistors 29 are blocked.

Provision is made for means H, for example, of the type described in theFR-A-2 631 902 for controlling the voltage of the grid of thetransistors 29 and cause these transistors to be conductive duringvariable and adjustable periods of time. Thus the means H ensure anelectric power supply for the drive motors 25-28 by chopping of thecurrent; the mean intensity passing through the drive motors and hencethe instantaneous available power will vary in accordance with thechopping rate (or cyclic ratio). The adjustment of this chopping rate isensured by action on the accelerator pedal; the more the acceleratorpedal is depressed, the longer the period of conduction of thetransistors 29, and vice versa.

Free wheel diodes 33, of which only one has been represented, aredisposed in parallel, with their anodes connected to the drain of thetransistors 29, and hence to the corresponding terminal of the drivemotors 25-28; the cathode of these diodes 33 is connected to the + line.A capacitor 34 is disposed between the cathode of the diodes 33 and thesource of the transistors 29.

The means described above with reference to FIG. 5 were already providedin the FR-A-2 631 902.

The means described below are specific to the invention and to thecontrol of the parking brake.

In this FIG. 5, the electric motor for controlling the parking brake hasbeen designated by the reference numeral 2 as in the preceding Figures.The relay Y will also be found again with its bar y already describedwith reference to FIG. 4.

The automatic control of the relay Y is obtained by means of the circuitE described below.

At its input, the circuit E includes a transistor 35, for example of thePNP type, whose emitter is connected to the cathode of the diode 33. Thebase of the transistor 35 is connected via a resistor 36 to the anode ofthe diode 33. A diode 37 is disposed between the base and the emitter ofthe transistor 35. The anode of the diode 37 is connected to the base ofthe transistor 35, while the cathode of the diode 37 is connected to theemitter.

The collector of the transistor 35 is earthed via several resistors 38,39, 40 disposed in series.

A ZENER diode 41 is disposed between earth and a point situated betweenthe resistors 38 and 39. The ZENER diode 41 is provided to limit thevoltage between this point and earth to a predetermined value, forexample, 17 V.

A point situated between these resistors 39 and 40 is connected via aresistor 42 to the non-reversing input of an operational amplifier 43disposed as a comparator; a capacitor 44 is disposed between thismidpoint of the resistors 39, 40 and earth.

The reversing input of the amplifier 43 is connected by a resistor 45 toa midpoint of a voltage divider formed by two resistors 46, 47 disposedin series between a + terminal at a specified voltage (for example 17 V)and earth. A reference voltage value is thus passed to the reversinginput of the amplifier 43. The output of this amplifier is connected tothe reversing input by a resistor 48. The output of the amplifier 43 isalso connected by a resistor 49 to the + terminal of the source of thereference voltage (+17 V for example) and to the anode of a diode 50.The cathode of this diode is connected by a resistor 51 to anon-reversing input of an operational amplifier 52 also disposed as acomparator.

A resistor 53 and a capacitor 54 are disposed in parallel between thecathode of the diode 50 and earth. These two elements 53, 54 form a timedelay circuit.

The reversing input of the amplifier 52 is connected by a resistor 55 tothe slider 56 of a potentiometer 57. A terminal of this potentiometer isconnected to the + terminal of the reference voltage (+17 V) by aresistor 58. The other terminal of the potentiometer is earthed via aresistor 59.

The output of the amplifier 52 is connected to the reversing input by aresistor 60. The output of the amplifier 52 is, moreover, connected by aresistor 61 to the + terminal of the source of the reference voltage(+17 V for example).

The output of the amplifier 52 is finally connected via a resistor 62 tothe base of a transistor 63, for example, of the NPN type. The emitterof this transistor 63 is earthed, whilst the collector is connected to aterminal of the coil of the relay Y, the other terminal of this coilbeing connected to the + terminal of a direct voltage source, forexample, at +24 V. A diode 64 is mounted in parallel at the terminals ofthe coil of the Y, the cathode of this diode being connected to the +terminal, and the anode being connected to the collector of thetransistor 63.

A resistor 65 is disposed between the base of the transistor 63 andearth.

Provision is made for a switch 66 to permit automatic or manualoperation. The position of the switch represented in a solid line inFIG. 5 corresponds to the automatic operation, the connection betweenthe +24 V terminal and the base of the transistor 63 via the resistor 67being cut.

When the switch 66 is rocked into the position represented in dashes,the connection between the base of the transistor 63 and the + terminalvia the resistor 67 is established. The transistor 63 is then madepermanently conductive, which ensures the energizing of the coil Y andthe rocking of the contact y producing the disengagement of the parkingbrake.

The pivoting terminal of the contact y is earthed. The terminal 20 ofthe relay Y whereon there bears the contact Y at rest (position in asolid line in FIG. 5) is connected to the terminal of a coil of anelectromagnetic relay K capable of actuating the change-over of acontact k between a rest position represented in a solid line in FIG. 5and an operative position represented in dashes. The pivoting terminalof the contact K is connected to a terminal of the motor 2; the terminalwhereon the contact k comes to bear when at rest is earthed; the otherterminal whereon the contact k comes to bear in the operative positionis connected to the + terminal of the power supply source (+24 V, forexample).

A diode 68 is disposed between the terminals of the coil of the relay K,the anode of this diode being connected to the terminal of the coilconnected to the contact y, the cathode being connected to the otherterminal which is itself connected to the contact 12 described above andcapable of cooperating with the conductive track 10a provided on a disk9a driven in rotation by the motor 2. The outer track 10a is open andincludes between its two ends an insulating space 11a similar to thespace 11 of FIGS. 1 to 4.

Provision is made within the track 10a for a second conductive track 10bwhich is concentric with the latter. This second track 10b is also openand includes between its ends an insulating space 11b diametricallyopposed to the space 11a. The contact 13, described above, bears on thedisk 9a in the annular zone of this track 10b. The contact 7 of FIGS. 1to 4 is replaced by a double contact 7a, 7b capable of bearingsimultaneously on the track 10a and the track 10b; this double contact7a, 7b is offset for example, by 90°, relative to the contacts 12 and 13which have the same angular position.

The contact 13 is connected to a terminal of a coil of anelectromagnetic relay L; the other terminal of this coil is connected tothe terminal 21 whereon the contact y comes to bear in the operativeposition. A diode 69 is mounted between the terminals of the coil of therelay L in a way similar to the diode 68 for the coil of K. A contact lcapable of changing between a rest position (represented in a solidline) and an operative position (represented in dashes) is controlled bythe coil of L. The pivoting terminal of this contact L is connected tothe terminal of the motor 2 opposite to that connected to the contact k.The terminal whereon the contact l bears at rest, is earthed; the otherterminal whereon the contact l bears in the operative position isconnected to the + terminal (+24 V for example). It will thus be seenthat the contacts k and l short-circuit the motor in itself in the restposition, which permits precise stopping.

The contacts 7a, 7b are connected to the operative terminal of thecontacts k and l as well as to the + terminal of the power supply source(+24 V).

The operation of the control device of FIG. 5 is as follows.

When the driver does not depress the accelerator pedal, in particularwhen the vehicle is stationary, the transistor 29 is blocked and thevoltage at the drain of this transistor, as well as at the anode of thediode 33 is equal to that of the + terminal of the power supply source,the electrical connection between the drain and the + line being ensuredby the windings of the motors 25-28. The transistor 35 is blocked anddoes not allow any current to pass.

The result is that the potential of the point comprised between theresistors 39 and 40 has a low value, near to 0. The output voltage ofthe amplifier 43, as well as the output voltage of the amplifier 52 areat the low level. The result is that the transistor 63 is not conductive(blocked state), so that the coil of the relay Y is not energized andthe contact y is in its rest position.

The shaft of the motor 2 and the cam 9a remain in the positionrepresented in FIG. 5 corresponding to the engagement of the parkingbrake, in which position the contact 12 bears on the insulating space11a. The coils of the relays K and L are not energized and the contactsk and l remain in their rest position.

When the accelerator pedal is depressed, the transistor 29 becomesconductive according to a chopping rate depending on the position of theaccelerator pedal. The drive motors 25-28 are supplied with electriccurrent and turn. The line 31 will have a lower voltage than that ofthe + terminal of the power supply source. The same applies to the baseof the transistor 35 which is polarized in the passing direction andbecomes conductive. A current will circulate in the series of theresistors 38, 39 and 40.

The voltage of the midpoint comprised between the resistors 39 and 40will increase. When this voltage is sufficient, the amplifier-comparator43 changes over and its output passes to the high level. The capacitor54 will be rapidly charged through the passing diode 50.

When the voltage at the terminals of the capacitor 54 reaches asufficiently high value, the amplifier-comparator 52 changes over inturn and its output passes to the high level, which renders thetransistor 63 conductive and ensures the energizing of the coil of therelay Y and hence its excitation.

The result is that the contact y passes from the rest position to itsoperative position (in dashes in FIG. 5). The coil of the relay L isthen energized via the contact 13 of the track 10b, the contact 7b andthe connection between this contact and the + terminal. The contact lwill pass to its operative position ensuring the energization of themotor 2, which will turn while driving the disk 9a, until the insulatingspace 11b arrives under the contact 13, that is to say, until the disk9a has completed a half turn.

The disengagement of the parking brake is then obtained, and since thepower supply to the motor 2 is stopped, the disk 9a is stopped in theposition that is diametrically opposed to that represented in FIG. 5.

The coil of the relay L is no longer excited and the contact l returnsto its rest position (a solid line).

When the accelerator pedal is again released and the transistor isblocked, the voltage on the point comprised between the resistor 39 and40 disappears. The output of the comparator 43 again passes to the lowstate (0 V). The capacitor 54 is discharged through the resistor 53,setting off the time delay for the engagement of the brake by hand.

When the voltage at the terminals of the capacitor 54 falls below acomparison value adjustable by the potentiometer 57, the output of thecomparator 52 changes over and passes to its low state actuating theblocking of the transistor 63. The coil of the relay Y is no longerenergized and the contact y passes into its rest position (a solidline).

Since at this moment, the disk 9a occupies a position diametricallyopposed to that represented in FIG. 5, the contact 12 bears on the track10a which ensures that the coil of the relay K is energized. The contactk changes over into its operative position, which ensures that the motor2 is energized, which turns while driving the disk 9a.

The rotational motion continues until the disk 9a has completed a halfturn to regain the position shown in FIG. 5 where the insulating space11a is located under the contact 12.

The power supply to the motor 2 ceases and the motor stops, the contactk returning to its rest position. The parking brake is engaged.

At no time is a short circuit possible in the power supply, even is therelays K and L were to remain stuck.

Referring to FIG. 6, one may see an embodiment of a parking brakecontrol device according to the invention in a golf buggy. Only aportion of the chassis of the vehicle has been represented, this portionbeing situated just ahead of the driver's seat (not represented).

A conventional brake pedal 71 is articulated round a transversehorizontal pin 72 carried in a low portion of the chassis 70 below thefloor 73 of the vehicle. The low portion of the pedal situated belowthis floor 73 is provided on both sides of the pin 72 with parallelshafts 74, 75 capable of serving as trunnions for the pulleys whereonthere are respectively wound the traction cables 76, 77 capable ofrespectively actuating the brakes (not represented) provided on thefront and rear wheels. Rotation of the pedal 71 in the anticlockwisedirection round the pin 72 so as to pass from the raised position (in asolid line in FIG. 6) to the depressed position shown in dots and dashesin this FIG. 6, produces a simultaneous pull on the cables 76 and 77,and hence the engagement of the front and rear brakes.

The parking brake control device is installed under the floor 73,slightly behind the pin 72. The electric motor 2 referred to above isfixed to the chassis 70. The motor 2 is generally combined with areducing gear 2a so that the shaft of the motor 2 is orientated parallelto the longitudinal direction of the chassis 70, whilst the shaft 4 ofthe reducing gear orthogonal to that of the motor, is orientatedtransversely.

The crank 3 for actuating the parking brake is fixed angularly at theend of the shaft 4 of the reducing gear.

The braking means of the parking brake are identical with the normalbraking device and the crank 3 is capable of exerting a pull on thecables 76 and 77, by means of the bottom part of the pedal 71.

Provision is made for a mechanical linkage by a loss of motion device 78between the crank 3 and a portion of the shaft 74 which projectsrelative to the pedal 71. The crank 3 is provided with a trunnion 79that is eccentric relative to the shaft 4. The device 78 includes ahelical tension spring 80 whose one end includes a straight extensionwhich forms the connecting rod 1. The end of this rod 1 forms a looparticulated on the trunnion 79.

The other end of the spring 80 is formed by a straight section bent backalong a relatively long loop 81. This loop 81 is capable of receiving inits concavity a projecting end of the shaft 74. The sides of the loop 81are sufficiently long for the shaft 74 to remain within this loop whenthe pedal 71 is completely depressed and when the crank 3 occupies theposition shown in a solid line in FIG. 6, corresponding to thedisengagement of the parking brake. When the engagement of the parkingbrake is actuated, the crank 3 completes a half turn and the trunnion 79comes to assume a position diametrically opposed to that represented inFIG. 6 relative to the shaft 4.

An optimum adjustment of the length of the spring 80 allows the top stopof the pedal 71 to be defined.

The spring 80 makes it, moreover, possible to cushion the pedal 71 whenbeing released.

The characteristics of the spring 80 make it possible to ensure acertain braking force and compensate the travel (greater or lesserclearance for the actuation).

The disk 9 with a conductive track of FIGS. 1 to 4 is fixed to the shaft4 of the crank. The spring 81 transmits the tractive force of the crank3 while damping any shocks to the shaft 74, which moves back to theposition shown in dots and dashes, the pedal 71 being driven in ananticlockwise rotational motion round the pin 72. The trunnion 75 isdisplaced forward and the braking device is actuated.

The accelerator pedal T has been represented in its rest position inFIG. 6.

The driver keeps the conventional use of the normal braking device byaction on the pedal 71, whilst the automatic control device of theparking brake becomes operative when the vehicle is stopped and theaccelerator pedal is released.

Provision may be made for means for sensing the speed of motion of thevehicle which are capable of only permitting the automatic engagement ofthe parking brake when the vehicle has stopped for a certain time, forexample, one second, or when its speed is less than that of apredetermined value. Such means could, for example, sense the voltage atthe terminals of the drive motors 25-28; when the vehicle continues toadvance in a freewheeling mode, the presence of a voltage due to therotation of the motors 25-28 operating as generators, would make itpossible to prevent the engagement of the parking brake until thevehicle has completely stopped and the accelerator pedal is raised.

Provision could also be made for a seat transducer disposed in parallelwith the preceding one, sensing the driver's weight. The engagement ofthe parking brake would only be actuated when the driver is no longerseated on his seat.

Provision may be made for a manual parking brake, in parallel with thecontrol device of the invention.

It should be noted that the invention concerns a parking brake controldevice which can be applied to any motor vehicle, although a golf buggyhas been more particularly considered in the above description.

The motor means actuating the parking brake could be constituted by apneumatic jack, a hydraulic jack or any other means equivalent to theelectric motor 2.

It is clear that the embodiment of FIG. 6 which concerns a brakingdevice by means of a cable is not restrictive. In the case of hydraulicbraking, the pedal 71 of FIG. 6, and hence the crank 3, would act on themaster cylinder.

I claim:
 1. A device operating a parking brake for a vehicle includingelectric motor means for actuating the brake, said motor means having adrive shaft, said device including control means for controlling theoperation of said motor means, said control means including a rotarycrank drivingly connected to a linkage member for actuating the brake,said crank being drivingly connected by said drive shaft to said motormeans for rotation thereof between an engagment position and adisengagment position, said device including a disk having twoconcentric, conductive tracks, one of said conductive tracks beinginterrupted by an insulating space, said disk being rotatably driven bysaid drive shaft, said device including brush means positioned to engagesaid tracks to provide an interruptable current path for electriccurrent for driving said motor means to effect movement of said crankbetween said engagment and disengagment positions.
 2. The device ofclaim 1 wherein the engagement and disengagement positions of said crankare diametrically opposed.
 3. The device of claim 1 wherein said crankis fixed on said drive shaft.
 4. The device of claim 3 wherein saidmotor means includes a reducing gear.
 5. The device of claim 1 whereinone of said tracks is an inner annular, closed track and the other ofsaid tracks is an outer, open track having opposite ends adjacent to andseparated by said insulating space, said tracks being electricallyconnected, said device including two diametrically spaced contactsbearing on said outer track, one of said contacts corresponding to saidengagement position and the other of said contacts corresponding to saiddisengagement position.
 6. The device of claim 1 wherein one of saidtracks is an inner annular, open track and the other of said tracks isan outer, open track, said one track having opposite ends adjacent toand separated by said insulating space, said other track having oppositeends adjacent to and separated by another insulating space, saidinsulating spaces of each said tracks being located diametricallyopposite one another on said disk, said tracks being electricallyconnected, said device including two contacts bearing on said trackseach having the same angular position relative to said disk, a doublecontact being provided to engage both of said tracks simultaneously. 7.The device as claimed in claim 1 wherein manual means are provided forthe actuation of the brake corresponding to the engagment anddisengagement positions, said manual means comprising a push button forstarting said motor means to move the brake from one of the positions tothe other of said positions.
 8. The device as claimed in claim 7 whereinan accelerator means is provided and said device includes an automaticcontrol element for disengagement of the brake when said acceleratormeans is actuated.
 9. The device as claimed in claim 1 wherein thevehicle is a golf cart having a pedal brake for slowing and stopping thecart, said motor means engaging said pedal brake through said linkagemember and a lost motion member allowing normal actuation of said pedalbrake.
 10. The device as claimed in claim 9 wherein said lost motionmember includes a helical tension spring having a straight extensionforming a connecting rod, said crank having a trunnion on which ispivoted a portion of said rod, said spring having an end opposite saidextension, said end of said spring having another extension bent to forma loop receiving a projecting end of a shaft operatively connected tosaid pedal brake.
 11. The device as claimed in claim 1 includingelectric drive motors for the vehicle, circuit means for delivering achopped current to said motors, another control means including acontrol relay for sensing the conductive state of a transistor forenergizing said electric drive motors.
 12. The device as claimed inclaim 11 including means permitting the manual actuation of thedisengagement of said parking brake.
 13. The device as claimed in claim12 including an accelerator pedal and a time delay circuit, said timedelay circuit is adjustable for actuating the engagement of said parkingbrake after the action on the accelerator pedal has stopped.